The present invention relates to a blood treating filter equipment incorporating a filter material to remove specific components efficiently from a large amount of blood.
Recently, a requirement has been imposed for a technology to remove a specific protein, leucocyte and the like contained in blood for the purposes of a blood extra-corporeal blood perfusion therapy for autoimmune diseases or inflammatory bowel diseases such as systemic lupus erythematosus, chronic or malignant articular rheumatism, multiple sclerosis, ulcerative colitis and Crohn""s disease, or diseases such as leukemia and cancer, or immuno-suppression before an organ transplantation operation.
The blood treating filter equipment used for these applications is required to have not only a high removability but at the same time an ability to treat a large amount (about 2 to 5 liters) of blood.
Until now, for example, a flat plate type nonwoven fabric filter composed of extra fine fiber or an equipment in which the filter is wound cylindrically (JP-A-62-243561) have been proposed as a leucocyte removal filter equipment. However, in a treatment of a large amount of blood as described above with these filters, a flow rate has to be reduced due to a possible large pressure loss in the equipment depending on a condition of the blood to be treated or when an anticoagulant is added insufficiently or mixed inadequately. This leads to a prolonged treatment time. Thus, a further improvement in removal efficiency has been required.
The inventors earnestly studied for a cause of the above-mentioned rise of the pressure loss in a filter. As a result, the following were revealed. In a conventional filter, large amounts of an object to be removed are trapped in the narrow channels in the filter impairing a smooth blood flow and increasing pressure. However, the rise of the pressure loss in a filter was not brought about as a result of an object to be removed as found in a conventional filter, but instead by characteristics specific to blood. In other words, the inventors found that the rise of the pressure loss was caused by platelets and other coagulation factors in blood which were activated by their sudden contact with a filter material forming a blocking membrane, disturbing a smooth blood low.
To avoid the,.problem described above, it is considered to be effective to enlarge a surface area of the filter. However, a simple enlargement of a filter size extremely impairs operability and productivity of the equipment. Furthermore, an enlargement of a surface area of a filter within a fixed volume of a filter material according to a conventional method lowers a removal efficiency for an object, due to a reduced filter thickness.
In view of the points described above, an object of the present invention is to provide a blood treating filter equipment with a high ability to avoid a pressure rise, which can inhibit local and abrupt activations of coagulation factors in blood, and remove target substances to be removed from a large amount of blood with a high efficiency without reducing a treating rate.
In order to achieve the object described above, the present invention comprises the following (1) and (2).
(1) A filter material, in which the following (a) and (b) are wound in an overlapped state, an end part of (b) is exposed to an outer circumferential surface or an inner circumferential surface of the filter material, and both end faces of the filter material are sealed liquid-tightly, wherein,
(a) is a blood treating filter layer, and
(b) is a sheet-like spacer layer through which blood flows more easily compared with said blood treating filter layer.
(2) A casing in which the filter material described above is installed, wherein the casing has a blood inlet and a blood outlet, the blood inlet leads to the side of an exposed end part of (b) on an outer circumferential surface or an inner circumferential surface of the filter material described above, and the blood outlet leads to the opposite side to the blood inlet on an inner circumferential surface or an outer circumferential surface of the filter material described above.